1. Technical Field of the Invention
The present invention relates to a gas turbine plant, particularly for reducing a pressure loss at a time of using a high pressure air generated by an air compressor as a cooling medium and supplying the high pressure air to a gas turbine shaft via an intermediate shaft.
2. Related Art
In general, as shown in FIG. 20, a gas turbine plant includes an air compressor 1, a gas turbine combustor 2, and a gas turbine 3, which are operatively connected, and is constructed in a manner that an air compressor shaft 4 and a gas turbine shaft 5 are connected by means of an intermediate shaft 8 including an outer cylindrical shaft 7 coaxially arranged in an inner cylindrical shaft 6.
The air compressor 1 is provided with a plurality of air compressor moving (rotating) blades 9 and air compressor stationary blades 10 along an axial direction thereof and compresses a sucked air so as to produce a high pressure air (highly pressurized air). Further, the air compressor 1 supplies a part of the high pressure air to the gas turbine combustor 2 as an oxidizing agent so as to generate a combustion gas therein, and then, supplies the combustion gas thus generated to a gas turbine stationary blade 11 and a gas turbine moving blade 12 of the gas turbine 3 so as to perform a work of expansion.
Moreover, the air compressor 1 supplies a portion of the remainder of the high pressure air to the gas turbine shaft 5 via a clearance section 13 and a space section 14 between the air compressor shaft 4 and the outer cylindrical shaft 7 of the intermediate shaft 8 so as to cool the gas turbine rotating blade 12 and its stud section (not shown).
Then, the high pressure air after cooling the gas turbine moving blade 12 and its stud section is supplied to the next stage turbine moving blade via a passageway 15, a clearance section 16 and a central hole 17.
On the other hand, as shown in FIG. 21 and FIG. 22, the air compressor shaft 4 and the gas turbine shaft 5 are both formed like a disc 18. The disc 18 is piled up like a laminated layer along an axial direction, and then, a tie-rod (not shown) is inserted into a bolt hole 19, thus, being formed as a disc shaft. Further, as shown in FIG. 22, the air compressor shaft 4 and the gas turbine shaft 5 are both formed with a blade stud section 20 having several concave-convex portions at an edge portion of the disc 18. The blade stud section 20 is provided with the air compressor moving blade 9 and the gas turbine moving blade 12.
As described above, in the conventional gas turbine plant, the air compressor shaft 4 and the gas turbine shaft are both formed like the above-described discs 18, and then, the discs 18 are piled up along the axial direction thereby to form a disc shaft so as to reduce a weight. Further, GD2 (G: gravitational acceleration; D: diameter of disc) is made relatively little, and a high speed rotation is stably performed.
By the way, in a recent gas turbine plant, in order to make high an output power per single plant, the gas turbine plant has a tendency to be made high temperature. For this reason, a cooling air is required much in amount so as to secure a material strength. However, in the gas turbine plant having the conventional structure, as shown in FIG. 20, when the high pressure air extracted from the air compressor moving blade 9 is supplied to the gas turbine shaft 5 as a cooling medium via the clearance section 13 and the space section 14, a swirling flow is generated. A flow of the high pressure air becomes worse resulting from the generated swirling flow, and for this reason, a pressure loss is increased. As a result, it becomes impossible to exhibit a convection cooling performance as a planned design value, thus being disadvantageous and providing a problem. In particular, recently, a capacity of single plant increases, and for this reason, even if the limited high pressure air is effectively used as a cooling medium, it is impossible to sufficiently utilize the convection cooling due to the increase of pressure loss. As a result, in the case of making the gas turbine plant high, there is an anxiety that an excessive thermal stress is locally generated in the gas turbine shaft 5, and a melting loss is generated in the gas turbine rotating blade.
It is an object of the present invention to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a gas turbine plant which can reduce a pressure loss of a high pressure air so as to effectively perform cooling at a time of supplying the high pressure air extracted from an air compressor to a gas turbine shaft via an intermediate shaft so as to cool the gas turbine shaft.
This and other objects can be achieved according to the present invention by providing a gas turbine plant, comprising:
an air compressor;
a gas turbine combustor;
a gas turbine, the air compressor, the gas turbine combustor and the gas turbine being operatively connected in series;
an air compressor shaft accommodated in the air compressor and composed of discs piled up along an axial direction of the air compressor shaft;
a gas turbine shaft accommodated in the gas turbine and composed of discs piled up along an axial direction of the gas turbine shaft; and
an intermediate shaft interposed between the air compressor shaft and the gas turbine shaft,
wherein at least one of the discs of the air compressor shaft and the discs of the gas turbine shaft are provided with bulged portions.
In a preferred embodiment, the bulged portion is formed so as to provide a hanging bell shape or trapezoidal shape.
In another preferred embodiment, each of the discs is integrally formed with a step-shaped flat portion to which a guide passage is formed.
In this embodiment, the guide passage is linearly formed towards a radial direction of the disc. The guide passage is provided, on an inner diameter side thereof, with a bent passage bent to a rotating direction of the disc. The guide passage is provided, on an outer diameter side thereof, with a bent passage bent to a direction reverse to the rotating direction of the disc. The intermediate portion between these inner and outer diameter sides may be formed to be linear.
The guide passage is formed so as to provide a convex curved surface which extends from the inner diameter side towards the outer diameter side in the reverse direction side. The step-shaped flat portion may be formed with a passage member to which the guide passage is formed.
In a further preferred embodiment, the intermediate shaft has an end face to which a projection piece is formed, the projection piece being formed with a guide passage. The guide passage formed to the projection piece is linearly formed towards a radial direction of the disc. The guide passage formed to the projection piece is provided, on an inner diameter side thereof, with a bent passage bent to a direction reverse to the rotating direction of the disc. The guide passage formed to the projection piece is provided, on an inner diameter side thereof, with a bent passage bent to a direction reverse to the rotating direction of the disc and also provided, on an outer diameter side thereof, with a bent passage bent to a rotating direction of the disc, and an intermediate portion between the inner and outer diameter sides is formed to be linear.
The guide passage formed to the projection piece may be formed so as to provide a convex curved surface which extends from the inner diameter side towards the outer diameter side in the reverse direction side.
The bulged portions extend in a radial direction of the discs from one side surfaces of rotation center lines of the discs.
The intermediate shaft is composed of an inner cylindrical shaft section and an outer cylindrical shaft section, at least one of which has an end face to which projection pieces are formed in an annular shape, the projection pieces being formed with guide passages.
According to the present invention of the structures and characters mentioned above, the gas turbine plant includes means (structure) for reducing the pressure loss of the high pressure air which is extracted from the air compressor stage and is supplied as a cooling medium to the gas turbine shaft, and preferably guiding the high pressure air. This means is located at least one of the discs of the air compressor shaft and the discs of the gas turbine shaft and the intermediate shaft for mutually connecting the air compressor shaft and the gas turbine shaft. Thus, it is possible to effectively perform convection cooling even if the flow rate of the high pressure air is limited and to maintain a high strength of the disc of the gas turbine shaft, and hence, to cope with high temperature of a gas turbine plant.
The nature and further characteristic features of the present invention are made clear from the following descriptions made with reference to the accompanying drawings.